Multicircuit quarter wave pulse jet engine



April 1951 A. G. BODINE, JR 2,546,966

MULTICIRCUIT QUARTER WAVE PULSE JET ENGINE Filed Jan. 12, 1948 4 Sheets-Sheet l M/PG/VE TO 166 32 21 6 33 5UPEECA/HR6EE Z? FIG. I. 415527-61 flow/v5, z/ie.

INVENTOR.

April 1951 A. e. BODINE, JR 2,546,966

MULTICIRCUIT QUARTER WAVE PULSE JET ENGINE Fild Jan. 12, 1948 4 Sheets-Sheet 2 79 66 I/ 7 5 2 612. 624 75 78 70 7! 73 l 72 P.

HEAT/7Y6- LM1VT 63 60 87 INVENTOR. 41554 76. flop/M5, fie.

April 3, 1951 A. a. BODINE, JR

MULTICIRCUIT QUARTER WAVE PULSE JET ENGINE 4 Sheets-Sheet 3 Filed Jan. 12, 1948 JNVENTOR. 445527- 6: flow/v5, (7k.

TTOEA/EK A ril 3, 1951 A. G. BODINE, JR

MULTICIRCUIT QUARTER WAVE PULSE JET ENGINE Filed Jan. 12, 1948 4 Sheets-Sheet 4 .m QQRWNSWNQE V m 5 E m N M Z a M 5 r 4w 7 M 5 63 4 w I Q Patented Apr. 3, 1951 MULTICIRCUIT QUARTER WAVE PULSE JET ENGINE Albert G. Bodine, Jr., Van Nuys, Calif.

Application January 12, 1948, Serial No. 1,733

15 Claims.

This invention relates generally to resonant quarter-wave pulse jet engines, and more particularly to resonant quarter-wave pulse jet enigines of multiple circuit and polyphase charac- The present invention is a continuation-inpart of my prior parent application Serial No. 439,926, filed April 21, 1942, entitled Resonant Wave Pulse Engine and Process (now abandoned), and also of my copending application Serial No. 753,898, filed June 11, 1947, entitled Pulse Jet Standing Wave Engine with Movable Wave Reflecting Means. See also my copending application Serial No. 783,662, filed Nov. 3, 194? as a continuation-in-part of my said parent application Serial No. 439,926, entitled Resonant Wave Pulse Engine and Process, and issued August 80, 1949 as Patent No. 2,480,626.

Resonant quarter-wave pulse jet engines utilized for jet propulsion have been disclosed in my prior applications, and a detailed description will not be required herein though reference may be made for that purpos to my aforesaid prior and copending applications. It will suiiice here to say that such an engine typically involves a substantially quarter-wave pipe, closed at one end and open at the other, with provision for burning increments of fuel and air in its closed end at a resonant frequency of the pipe so as to create intermittent positive pressure pulses establishing a standing wave therein. Auxiliary air may be introduced to the closed end of the pipe, and this air, together with products of the combustion, travels down the pipe to be discharged from the open end thereof. Air is also drawn laterally inward toward the open end of the pipe and thence up the pipe for a distance, to be then discharged straight rearwardly from the open end of the pipe.

Such engines in large power size have the disadvantage of excessive production of vibration and noise, and limitation on poweroutput; and the general purpose of the present invention is the provision of a quarter-wave pulse jet engine ,which overcomes these disadvantages.

The engine provided by the present invention may be regarded broadly as a multiple circuit wave pulse jet engine, by which term I refer to a wave pulse jet engine having two or more resonated pipes, with either uniform or non-uniiorm phase relations between them. In distinction thereto, and by analogy with electrical engineering practice, I employ the expression po1yphase engines to denote the narrower class of multiple circuit engines with substantially uni- 2 form phase relations. Thus an engine having two pipes operating with waves of 180 phase dif ference is a two-phase polyphase engine, one

having three pipes with waves of phase difference is a, three-phase polyphase engine, etc. In general, the benefits of the present invention are gained in a multiple circuit engine having non-uniform phase relations, but these advantages are realized to the maximum extent when the phase relations are made uniform throughout.

A primary object of the invention is the provision of a multiple circuit quarter-wave pulse jet engine, and a further object is the provision of such an engine characterized by uniform phase relations, i. e., polyphase operation.

A multiple circuit quarter-wave pulse jet en-, gine in accordance with the invention may be one whose pipes or resonant fluid columns are separate from one another, 1. e., have no internal intercommunication, or one whose fluid columns do communicate with one another internally of the apparatus. In the'latter instance. the communicating fluid column may have but a single fluid discharge opening. In both types, polyphase operation may be established automatically, by virtue of acoustic self-coupling. The couplings may also, or alternatively, be of mechanical character.

Multiple circuit quarter-wave pulse jet engines in accordance with the invention. may be arranged with the resonant pipes either side by side, or in staggered or longitudinal spacing.

In my multiple circuit engines the sound waves emanating from the several pipes thereof tend to cancel one another at a distance from the engine,

with the result that objectionable noise is reduced. In the region of the jets of the several pipes, on the other hand, the waves interact upon one another in such a way as to efiect a desir-., able acoustic self-coupling leading tov polyphase operation. In this regard, it will later become .ap-: parent that substantial gas velocity oscillations occur at the discharge opening of the several pipes, these discharge openings being the locations of velocity anti-nodes of substantially equal acoustic impedance. When these discharge openings are located in correct proximity to one an: other, the oscillations tend to synchronize so as to give polyphase operation. Thus two quarterwave pipes having automatic valves and sub-.- stantially equal resonant frequencies operating de by side with sufficient acoustic coupling will automatically fell into step, with their waves out of phase with one another.

Polyphase operation has the further advantage of giving an efiect of higher frequencies where both noise and vibration are more greatly attenuated at a distance, where an observer might be standing. Further, by dividing the total power of an engine between several circuits, each explosion is of correspondingly reduced intensity, to obvious all-around advantage.

The advantages of multiple circuit pulse engines mentioned in the foregoing are realized even with random phase relations, with no positive or mechanical linking between circuits. However, as already mentioned, the several units of a multiple circuit engine tend automatically to link together by acoustic self-couplingand thus to operate with polyphase relationships.

As a further consideration, it is known thatthere is a maximum effective diameter (approximately where 7\=wave length) for the pipe of a jet propulsion apparatus of the present type. Above that value, wave reflection becomes bad at the open end of the pipe. Increase in the diameter of the pipe for added power, without increase in the wave length, and thereforein the pipe length, is accordingly limited. The use of a multiple circuit engine permits increase in power without in crease in pipe length.

The invention will be further described in con nection with the accompanying drawings showing present illustrative embodiments thereof, and wherein:

Figure 1 is a somewhat diagrammatic partly elevational and partly sectional view showing one embodiment of the invention;

Figure 2 is a similar view showing another illustrative embodiment of the invention;

' Figure 3 is a medial longitudinal sectional view of a still further illustrative embodiment of the invention;

* bustion within chamber I5 (being driven by that combustion) and operates to transmit the pressure pulses developed in the combustion chamber to the fluid column in pipe ll].

Cooperating with a suitable valve seat formed 7 within head I4 is an intake valve supplied with Figure 4 is a perspective view of the internal parts of the embodiment of Figure 3;

Figure 5 is a medial longitudinal sectional view of still another illustrative modified form of the invention;

, Figure 6 is a somewhat diagrammatic view, partly in section. showing a modification of the embodiment of Figure 2;

Figure '7 is a side elevation, partly in longitudinal section, showing another modified embodiment of the invention; and

Figure 8 is a section taken on broken line 88 of Figure '7.

Figure 1 of the drawings shows a multi le circuit polyphase wave pulse engine of a type in which synchronization is accomplished by mechanical coupling. Three sonic pipe units l6 are employed, positioned side by side, and in a general way parallel to one another, though they may be arranged with a small angle between their respective longitudinal axes for an optional purpose to be mentioned hereinafter. These sonic pipe units I ll are identical with one another, and are provided with identical combustion means, so that a description of one will serve for all. Each pipe unit I I] thus has a somewhat flared open end i 2, through which air is alternately drawn in from virtually all directions and then discharged straight rearwardly to produce a jet propulsion thrust. I'he opposite end'of the pipe "lil has a flange connection I3 with a closure head It defining a somewhat restricted combustion space I5.

a combustible mixture through a pipe 2i to which the mixture is fed from a supercharger 22, the mixture being formed by carburetor 23. Also cooperating with a suitable valve seat formed within head I4 is an exhaust valve 25 controlling the flow of exhaust gases through a passage 26. The intake and exhaust valves are operated in sequence by cams 2'? and 28, respectively, on a cam shaft 23 which drives the supercharger 22 and magneto 3B, and which is here shown as driven by a drive means 3|, which may consist of any suitable gear means interconnecting with a single drive shaft 32 driven by a main drive unit 33. The latter may be any speed-governed drive,.such as an electric motor, internal combustion engine, turbine, etc. 7

As an alternative or supplemental fuel supply means, there may be provided a fuel injector pump 3 driven from cam 34a on cam shaft 29 and acting to meter liquid fuel directly into the combustion chamber through a suitable spray type injection nozzle 34b. Fuel can be mixed with the air in the carburetor 23 to form a lean mixture delivered to the combustion chamber through intake valve 26, and additional fuel in liquid state can be supplied, preferably during periods of high pressure in the combustion chamber, by use of the injector pump. Alternatively, the carburetion system or the injection system may be utilized individually, and if it be desired to inject all the fuel into the combustion chamber, the necessary air for combustion will be supplied through the intake valve from the supercharger. In the latter case, the combustion is timed and synchronized by air introduction under control of the cam driven intake valve. The magneto and cams 21, 28 and Sea are of course arranged to provide the desired operative sequence of events including introduction of fuel, ignition (as by use of spark plug 35 connected to magneto 3G3) and exhaust of the combustion products.

The events of the operating cycle include, in sequence, (1) delivery of the fuel charge to the chamber 15 upo'nopening of the intake valve and movement of the vibratory diaphragm It toward the right, (2) compression of the admitted fuel charge on return movement of the diaphragm (toward the left), (3) ignition of the fuel charge and consequent creation of a positive pressure pulse which drives the diaphragm back toward the right, causing the pressure pulse to be trans} mitted to the fluid column, and (4) opening of the exhaust valve and return of the diaphragm to scavenge the combustion chamber.

The speed of the cam shaft 29 of each unit is such that the explosions generated in combustion chamber I5 occur at such frequency as will establish a condition of standing wave resonance in the fluid column within the pipe i0,

the pipe behaving substantially as a quarter-wave Organ pipe, with a pressure anti-node region P adjacent the closure formed by diaphragm l6, and. with a velocity anti-node V at the open end l2. It will, of course, he understood that for a pipe of. given length, there will be a correspondingexplosion frequency necessary toestablish the desired resonant operation, and the cam shaft 29 is driven at a speed to achieve such a condition. One method of accomplishing this purpose is to note'the peak reading of a pressure gauge 38 communicating with the pressure anti-node regionP of the apparatus. This gauge will show a maximum reading at resonance. The reading on the gauge 36 will indicate the magnitude of the propulsive thrust, since the thrust results, at least in part, from the action of each wave pulse against the diaphragm it in accordance with radiation pressure principles set forth in my aforesaid application Serial No. 439,926.

follows: The explosion within chamber 55 creates a-;pressure disturbance producing a positive pressure pulse which moves diaphragm it to the right, thereby transmitting the positive pressure pulse to the end of the fluid column within the pipe l0 and thence toward the right along the fluid column, the wave traveling with the speed of'sound to the open end l2 of the pipe, which expands it into the open atmosphere. Normally the diaphragm will be substantially at its extreme position toward the left at the instant of explosion. At a time substantially 90 following the explosion, the diaphragm passes through the midposition of its forward or power stroke travel toward the right, and at such time transmits peak positive pressure to the end of the fluid column. The diaphragm will thereafter complete its stroke to the right and then move through a return stroke (leftward) by virtue of the energy stored in its stressed compliance.

The positive pressure pulse launched down the pipe by the described forward stroke of the diaphragm is reflected from the open end of the pipe as a negative pressure pulse (wave of rarefaction),the peak of which arrives at the diaphragm one-half cycle after the positive pressure pulse peak at the diaphragm and just as the diaphragm is at the mid-point of its return stroke (leftward) The diaphragm continues toward the left, and this movement together with the negative pressure pulse already mentioned creates a substantial pressure depression in the region immediately to the right of the diaphragm. The said return stroke of the diaphragm (toward the left) operates to scavenge the combustion chamher, the exhaust valve 25 being open at this time. I

The described negative pressure pulse is reflected bythe diaphragm as a negative pressure pulse moving toward the right, which is reflected from the open end to return a half-cycle later as a positive pressure pulse that arrives at the diaphragm with peak positive pressure as the diaphragm passes with maximum velocity through the mid-position on its next forward stroke (toward the right). Apositive pressure peak is thus built upto the right of the diaphragm'while a suction is created within chamber l5 by whichfuel is taken in through the then open intake valve 28. A positive pressure pulse is thenreflected from the diaphragm, and returns a halfcycle later (after reflection at the open end) as a negative pressure pulse reaching the diaphragm with peak pressure as'the latter passes through the mid-position of its compression stroke (leftward). The negative pressure pulse is in turn reflected by the diaphragm and a half -cycle later will return from the open end as a positive pressure pulse arriving with peak positive pressure just as the diaphragm passes through its midposition on the succeeding power stroke. positive pressure peak will thus again be created to the right of the diaphragm as the diaphragm crosses the mid-point of its forward power stroke, and the succeeding cycle proceeds as before. The maximum pressure in the chamber [5 occurs instantly after the explosion, when the diaphragm is in its extreme leftwardposition. The maximum positive pressure in the region immediately to the right of the diaphragm occurs of the cycle later, with the diaphragm at the half-way point of its return stroke, moving with maximum velocity. The pressure wave at the head end of the fluid column in pipe It thus lags by 90 the pressure events in the combustion chamber, the

intervening diaphragm functioning as a coupling introducing substantially a 90 phase lag.

It will be seen that'the pipe IE] behaves as a quarter-wave organ pipe, cyclically excited by intermittent combustion generated pressure pulses at a sub-multiple (here one-half) of its resonant frequency. In accordance with quarter-wave pipe theory, a standing wave is established in the pipe, with a pressure anti-node P adjacent the .diaphragm it, and a velocity anti-node V at the open end or tail I2. At the pressure anti-node P, as well as within the combustion zone [5, alternate positive and negative pressure peaks are experienced, and these create a radiation pressure thrust on the diaphragm in accordance with principles explained in my application Serial No. 439,926. At the pressure anti-node zone P, to-and-fro oscillation of the fluid is, of course, minimized. At the velocity anti-node region V, however, the air moves to-and-fro into and out of the open end of the pipe with substantial amplitude. Outside air is alternately drawn into the end of the pipe from virtually all directions, and expelled in a rearward axial direction, thereby creating a thrust by jet discharge. I

The foregoing description or" operation is confined to a single unit. To secure polyphase operation, the cams on the three cam shafts 29 are arranged 126 out of phase, which of course equally spaces the explosions (and therefore the jet discharge pulsations) of the three units at phase relationship. The beneficial results of this polyphase operation include increased frequency, increased attenuation of noise and vibration, and reduction of noise at a distance from the engine by mutual cancellation of the three sound waves delivered out-of-phase by the three units. In addition, improved power output can be achieved in such a polyphase engine as compared with a single pipe unit having a pipe of a cross-section equal to the total cross-section of the three employed in the present embodiment of the invention.

The use of the three pipes, with small angles between their longitudinal axes, as in Figure 1, also permits directional control of a craft to which the engine may be attached. Thus it should be evident'th'at cutting out either of the outside pipes will'vary the resultant direction of thrust in the apparatus, and that various combinations" are possible to achieve a substantial degree of directional control.

{Reference is next to the embodiment of Figure 2, showing a multiple circuit engine employing acoustic coupling, in this specific instance, accomplished internally of the apparatus. In this embodiment there are provided two quarter-wave pipes. 59 and having closed forward ends 52 and 53, respectively, and the far or rearward end portionsof which are curved towards one another and joined. The joined rearward ends of the pipes are provided with a single, common jet discharge opening or outlet 55. It will thus be seen that the two pipes 59 and 51 contain gas columns which are in internal communication with one another.

The closed or forward ends of the two pipes 59 and 5| are connected to wave-controlled combustion means 56 and 51, respectively, which may be of various natures, and two examples of which are shown connected to the two pipes 59 and 5|. Each such wave controlled combustion means comprises generally a means for burning a combustible charge at the resonant frequency of the corresponding pipe, so as to establish a quarterwave standing wave therein. Each such standing wave will be characterized by the appearance of a pres-Sure anti-node at the closed end of the pipe, designated at P and P for the pipes 59 and 5|, respectively, and a velocity anti-node V at the rearward portions of the pipes, immediately adjacent the common discharge outlet 55. With no mechanical interconnection between the two combustion means 55 and 51, the two standing waves of the two pipes 59 and 5! are synchronized owing to a push-pull interaction of the gas columns at the velocity anti-node region V so as to establish polyphase operation with 180 phase difierence between the two sides of the system.

The wave controlled combustion means 56 as here shown includes a fuel injection nozzle 69 adapted to introduce fuel to combustion zone BI and connected by fuel line 93 to injection pump 64 which delivers a charge of fuel each time its plunger 55 is raised. Pump 64 is actuated by an arm 66 pivoted at 6? and operatively connected to rod 58 attached to diaphragm 59. This diaphragm works in a housing 19 forming chambers H and 1'2 therein, which are in restricted communication through a small orifice 13. Chamber ?2 is substantially sealed from the atmosphere at the junction of the rod 58 and the housing. Chamber ii is in relatively open communication with combustion zone 5! through orifice M which is'larger in size than orifice l3. An air intake valve #5 opens into combustion zone 6! and provides a stem terminating'in a pressure plate '55 disposed to be engaged by arm 55 to open the valve against a valve spring 11. Valve 15 controls the flow of air from air intake passage 19 formed by intake pipe 19, the far end of which is preferably bent and flared to provide a mouth SI for the air stream created by motion of the apparatus.

In this embodiment, compression in combustion zone BI is depended upon to cause ignition, such compression resulting from pressure peaks owing to the previously mentioned standing wave.v However, to aid the compression ignition, the combustion chamber may provide a collar-like member 85 providing a slightly restricted passage 86 opening on the combustion zone 9!. The heatof iii this member will be sufficient',yat the value of the:

pressure .pulses in the sonic column, to ignite the fuel in a manner similar to that'employed in so-called hot tube or hot head combustion engines. To aid in the starting of the device, the

member may be heated by such a means as anannular electric heating element 8'! which can be used within or adjacent the member 85 to supply initial heat for starting.

The wave control combustion means 5'! may be of exactly the same character .as the means 56, though it is here shown in somewhat different form. Here, ignition depends upon spark plug 99 connected to intake coil 9|, the low voltage'circult of which includes the source of current 92 and a make-and-break switch .93 similar to that employed in conventional automotive practice. Switch 93 is actuated by plunger 94 connected to diaphragm 95 urged downward by spring 96, the low side of the diaphragm communicating through passage 91 with the fluid column 69 at zone P. Upon the appearance of a positive pres sure pulse at P, diaphragm 95 moves upward to open switch 93 and break the low voltage circuit, thus inducing in the high tension winding a voltage sufilcient to cause the plug 99 to spark. The sparking of this plug will be synchronized with and by the appearance of pressure pulses in the zone P.

A combustible mixture is introduced into zone P through intake valve I99, which is ofan .ill-L wardly opening spring-loaded type, so that it opens whenever the pressure in, a fuel induction passage 89! exceeds the pressure at P by a pre-' determined amount, thus insuring delivery of a combustible mixture during period of rarefaction at P, the charge being later ignited upon the appearance of the following pressure pulse at this zone. A supercharger I92 supplies the airfuel mixture to passage I91, the mixture being supplied to the supercharger via carburetor I93 and pre-heater I94 surrounding pipe 5!.

Operation is as follows: an explosion in zone P of pipe 59, caused by burning fuel in combustion zone 6!} establishes a positive pressure pulse which travels at the speed of sound through the' fluid column in the pipe 59 from the closed end thereof in the direction of the discharge outlet 55. In a similar manner, an explosion in zone P of pipe 5|, caused by burning fuel in the combustion zone thereof, establishes a similar positive pressure pulse traveling at the speed of sound through the fluid column in the pipe 5| in the direction of the common discharge outlet 55.

It should be evident that the two positive pressure pulses thus generated in the'two pipes 59 and 5| will, if created substantially simultaneously, buck one another at the velocity anti-node zone V. The tendency, however, is for the two interacting waves quickly to assume a relationship of phase difference, where the two positive. pressure waves in the two pipes 59 and 5! .no longer buck, but operate in a push-pull'fashiorr, each aiding the other. Thus the powerful velocity oscillations of the two gas columns at the velocity anti-node zone V acoustically couple the two sides of the system, synchronizing the two standing waves to operate with 180 phase difference. The explosions at the combustion zones of the two pipes then occur alternately, in 180 phase opposition.

Each explosion at zone P accordingly sends a positive pressure wave traveling toward the right in pipe 59. At the instant of this explosion in pipe .59 .a .rar a Qn prevails at zone P, in i e 5|, causing intake valve I to open, and fuel to be discharged to the zone P. At the subsequent peak of positive pressure in zone-P, plug 30 sparks as already described to ignite the fuel charge at P, so that a positive pressure wave is launched The subsequent peak of positive pressure in zone 6| compresses this charge to the point of selfignition, whereupon the cycle is repeated. The result is the creation of a standing wave characterized by the pressure anti-node P at the head end of pipe 53, a pressure anti node P at the head end of pipe and a velocity anti-node V at their point of intercommunication. Combustion gases progress toward the right in both pipes 50 and 5| and are discharged via outlet 55 to form a propulsive jet. A propulsive thrust is also obtained by radiation pressure principles as discussed fully in my parent application Serial No. 439,926. See also my Patent No. 2,480,626.

The embodiment of Figure 2 thus consists of a two phase, polyphase engine, characterized by lack of mechanical intercoupling between the two pipes, and by the provision of acoustic selfcoupling internally of the apparatus. It should be evident that the embodiment of FigureZ illustrates a type of acoustic coupling for polyphase operation which is operative whether or not the coupling is made effective internally of the pipes. Figure 6 shows somewhat diagrammatically, a modification of Figure 2 in which acoustic coupling is achieved externally of the pipes. Two pipes 5M and 5Ia may have at their closed forward ends wave controlled combustion means 56a and 51a, like the corresponding means 58 and 5'. of Figure 2, and may have their rearward end portions placed side by side, and open at their extremites. Standing waves are established in both pipes, with pressure anti-nodes at P and P and velocity anti-nodes at V and V. The velocity anti-node regions are characterized by powerful velocity oscillations in the surrounding fluid, both within the end portions of the pipes,

and in the general area immediately around and polyphase operation (equal phase angles) with no other interconnection between the two sides of the system.

Reference is next directed to the embodiment disclosed in Figures 3 and 4, showing a polyphase engine enclosed in a streamlined shell, and employing certain further improvements. Numeral I designates generally a cluster of sonic pipes I3I, symmetrically disposed about a central long-itudinal axis, and in this instance five in number. Each of these pipes has a forward end closure I32, and an open rearward end I33. Connected to the head ends I32 are fuel and air intake pipes I34, which converge in a forward direction and merge with the five segment-like cells or passages I35 of a fuel and air intake cylinder I35. The latter consists of a cylindrical shell, divided by longitudinal, radial walls I37, so as to form passages open at the forward and rearward ends of the cylinder. The passagesI35 at the rearward end have already been described as connected to the intakepipes I34. The forward ends are open for intake of fuel and air.

Numeral I40 designates an elongated streamlined shell, preferably of circular section, having its greatest section at approximately its longitudinal midpoint and being slightly convergent toward its open or tail end I4 I, and somewhat more convergent toward the open forward end or nose I42. The pipes I3I are disposed within the rearward portion of this shell, and the cylinder I36 vis located somewhat forwardly, and on the 1ongitudinal central axis of the shell. Suitable supporting and bracing means may be providedfor the support of the cylinder I36 andpipes I3I within the shell, as indicated at I44. Disposed in the forward end portion of the shell, forwardly of cylinder I36, is a streamlined body I50 supporting a fuel distributor pipe I5I-, together with a drive motor I52 for the latter. This body I50 is annularly spaced inside the forwardly converging walls of the shell, so as to provide an ample air flow passage therearound. Thus air taken in at the open nose I42 flows rearwardly around the body I55, a portion of it entering the passages I35 for direct intake into the pipes I3I, and another portion flowing rearwardly past the outside of the cylinder HE, and around the outsides of the pipes I3I, to serve a later described desirable function atthe rearward ends of the pipes I33.

The fuel distribution pipe I5I consists of an axial pipe portion I60 mounted in bearings I54 and I55 in body I58, and having mounted thereon the rotor I53 of. electric motor I52, the stator I64 of the latter being fixed within the body I50 as indicated. A fuel passage I65, supplied by means of fuel line I66, supplies fuel to a, chamber I63 surrounding a short lengthof pipe portion I69, this chamber I68 being packed off around member I66 by means of suitable packing glands ItI and IE2 as indicated. AperturesIlH in pipe portion I60 permit fuel to enter the interior thereof. Rearwardly of the body I50, the pipe I5I has a portion Ill extending laterally from the axial portion I60, and extending rearwardly from the extremity of portion III is a fuel injector nozzle II2, the latter being located immediately forwardly of the cylinder I3 5,- so as to inject fuel into the several passages I35 depending upon its position at any given instant. It will be evident that the motor I52 will rotate the pipe I5I, and so cause the nozzle I12 to project fuel charges into the several passages I35 in turn.

Each pipe I34 together with the corresponding passage I35 is preferably of a length equal to onequarter the wave length corresponding to the fundamental resonant frequency of the pipe I3 I. With such dimensions, the juncture of the intake pipe I34 with the pipe I3I may be valveless', as explained in my copending application finenesruary 15, 1947, Serial N6. 728,766, Standing Wave Jet Propulsion Apparetuswitn ValV ess Air Intake Conduit, in which said feature is disclosed and claimed. 7 I 1 Considering first the operationof a ere pipe I3I, air intake pipe I34 with the correspdnd-i-ng passage I35 delivers a continuous flow of air to the head end region of pipe I 3!; and an intermittent fuel charge thereto, dependingupoii the timing of fuel distributor I5I. The mixture is ignited as by means of spark plug I75, and the resulting explosion creates a positive pressure pulse or wave of condensation traveling with the speed of soundin the column of gas in pipe I 3 I toward the rearward open end of the latter. This "11 wave will be reflected from said open end of a negative wave or wave of rarefaction, which will in turn be reflected by the head I32 as the wave of condensation. The last mentioned wave of condensation, arriving at the head end region of the pipe, increases the pressure thereat, and the fuel mixture introduced via the pipe I34 subsequent to the last explosion has its density within the head end region of the pipe thereby sufficiently increased to cause a second explosion. The flame never completely extinguishes between explosions, but the reduced pressure and fuelair mixture density prevailing between positive pressure peaks inhibit and attenuate combustion to a point that only suflicient flame is retained to insure explosive combustion on subsequent pressure peaks. Thus it will be seen that the spark plug need be employed only on starting, compression ignition being available thereafter. The pipe I3I behaves as a quarter-wave organ pipe, cyclically excited at its resonant frequency under positive control if the fuel distributor pipe I5I is operated at such a speed as to provide fuel charges to the pipe at the said resonant frequency of the pipe. It is therefore desirable to provide the proper relationship between the speed of the fuel distributor motor I52 and the fundamental frequency of the pipe I3l. The relationship will be correct if motor I52 rotates at a R. P. M. equal to the fundamental wave frequency of the pipe I3I.

The zone P will be understood to be the location of a pressure anti-node P, where alternate positive and negative pressure peaks are experienced. At the velocity anti-node region V gas flows to and fro into and out of the pipe with substantial amplitude. Air supplied by the air stream flowing rearwardly around the pipe I3I, is drawn first into the end of the pipe I3I, and then expelled in a straight rearward direction, along with a quantity of combustion gases, to develop a jet propulsive thrust.

It will be evident that the fuel distributor pipe I5I delivers fuel charges to the several intake pipes of the cluster of sonic pipes I3I in succession, thus positively establishing polyphase, which in this instance is'fi've phase.

The apparatus of Figure 3 has the benefit of increased frequency, reduced noise production, augmented power for a given length of sonic pipe, and general all around simplicity. The polyphase operation is here established by the synchronizing fuel distributor, and acoustic coupling is not required. It should be evident, however, that a cluster of pipes placed side by side as in Figure 3 will automatically assume a moderate degree of polyphase operation by acoustic self-coupling in the regions of the discharge openings of the pipes I3I even though the synchronous fuel distributor not be employed. Such intercoupling resembles that described in connection with the embodiment of Figure 2, where the gas columns in the two sided system are in communication internally of the apparatus. Similar coupling, though of course not so strong as in the case of Figure 2, will result when the gas columns communicate externally of the pipes, as in Figure 6. Such acoustic intercoupling will occur with pipes disposed and spaced as indicated in Figure 3.

In the previously discussed embodiments of the invention, the sonic pipes are disposed in side by side relationship. They may also be disposed in staggered or longitudinal spacing, and the em- 12 bo'diment disclosed in Figure 5'is illustrative of such an arrangement.

The apparatus of Figure 5 is shown to employ an external streamlined shell 2%, preferably of circular section having its greatest thickness at approximately its mid-section, and being slightly convergent toward its open tail end 2m, and also somewhat convergent toward its open forward end or nose 282. A streamlined diffuser body 205 is positioned on the longitudinal axis of shell 200 in the forward portion of the latter, providing an annular air passage 206 extending therearound in a rearward direction. Rearward of the diffuser body are a plurality of longitudinal rows of longitudinally spaced or staggered quarter-wave pulse jet units ZIU. In the present embodiment,

for simplicity, there are two of these rows of units, diametrically opposed from one another, though it will be understood that additional rows may be provided. In the present embodiment, each of the rows consists of three of the units 2"], and these units 2I0 are, generally speaking, of the same type as the individual pipes I3I of Figure 3. See also my aforementioned prior ap-' plication Serial No. 728,766, for a more complete discussion of this type of unit.

Each unit 2I0 has a sonic pipe 2 I 5 formed with an end closure 2H5 upstream of the air flow through the shell 260, and with an open end 2I'I, the latter projecting, with clearance, into an annular passage or port 2I8 extending outwardly and rearwardly through the side of the shell 200. The head end of each of the pipes 2 I 0 is also fitted with a quarter-wave air and fuel intake pipe 2 I9 of the type completely described in my aforesaid application Serial No. 728,766, said pipe 2I9 being provided with an injector nozzle 220 fed by a fuel line 22I.

The several fuel pipes 22I are supplied with fuel from a distributor pump 222 located inside diffuser body 205, said pump being driven by any suitable means such as an electric motor 223 and fed with fuel by way of fuel line 226 from fuel tank 221 located in the forward portion of body 205. It is to be understood that the pump 222 is designed to feed increments of liquid fuel successively to the several fuel lines, whereby the several pulse jet units 2I0 will be supplied with fuel charges in a predetermined succession. Various firing orders may be provided. One simple arrangement is to design the pump 222 to deliver charges of fuel to the three units 2H) of each longitudinal row in succession, at uniform timed intervals, so that they will operate in a three phase fashion. The pump can be designed to deliver charges of fuel to the diametrically opposite row in exact synchronism with the first row, so that three phase operation is obtained, with corresponding units on opposite sides of the apparatus firing simultaneously. Alternatively, the pump 222 can be designed to deliver fuel charges to the units 2H of the second row in between the delivery of fuel charges to the units of the first row, thus giving six phase operation, with externally experienced sound at doubled frequency.

In operation, air taken into the apparatus through the nose 202 will enter the several intake pipes 2I9, and will form mixtures with the fuel charges supplied by the injector nozzle 22!), which mixtures are delivered to the head end regions of the pipe 2I5, the order of delivery being of course predetermined in the design of the pump 222. Ignition may be initiated as in the earlier described embodiments, and in operatlon, each unit will deliver combustion gases from its rearward open end in the form of a propulsive jet which discharges through the side of the shell 200 by way of the orifice provided. Operation is characterized by the establishment of a pressure anti-node P in the head end of the pipe 2H), and a velocity anti-node V at the open end thereof. It should be unnecessary to again describe the operating cycle, which has already been adequately' discussed in connection with previous embodiments. Attention is, however, directed to the fact that the air stream flowing rearwardly through the shell 206 supplies air to the velocity anti-node regions V of the open ended pipes 2 I5, such air being drawn laterally in and then up the pipes for a distance, and thereafter expelled straight rearwardly of the pipes to add to the mass of the jet discharge.

The pipes 2I5 of the embodiment of Figure 5 I are shown as provided with some convergence in the rearward direction, this being of advantage for a reason disclosed in my Patent No. 2,480,540. In the specific arrangement of Figure 5, the convergent rearward end portions of the first and second units 2 I 8 in each row are somewhat overlapped by the intake pipes 2I9 of the units immediately to the rear, thus giving what might be, regarded as as taggered relationship. Disregarding the intake pipes 2 I 9, however, the main pipes 2I5 of the successive units in Figure 5 form a longitudinal row, with longitudinal spacing between pipes.

Reference is next directed to the embodiment illustrated in Figures 7 and 8. Numerals E36 and I3I show a symmetrical pair of convergent. hornlike resonant pipes or cavities providing a pair of generally parallel fluid conduits, the. small or neck ends of which communicate with a piston chamber I32 of a two cylinder, free piston engine designated generally by numeral I33. Engine I33 employs a pair of opposed, axially alined engine cylinders I34 and I35;

Each of cylinders I34 and I35 joins the chamber I32, which is defined by a cylindrical. sidewall. I 36, and angular endwalls I37, disposed at angles of approximately 60 to the axis of the cylinders, as clearly shown in Figure 7; The smaller end portions of the conduits. I30 and I3I are curved somewhat toward one another and joined, to the angular walls I31 of chamber I'32 at substantially right angles thereto, the walls I31 being ported so that the conduits I33 and I3I communicate freely with the chamber I32. The far or open ends of conduits I3lland I3I discharge in substantially parallel directions, perpendicular to the axis of the engine cylinders I34 and I35. As already mentioned, the conduits I30 and I3I are preferably somewhat divergent, though not as divergent as might appear from Figure 7, there being preferably a moderate convergence' in the planeat right angles to-Figure 7", as will appear from an inspection of Figure 8. Overall, the conduits I33 and I3I may be con- 'sidered to have, preferably, a small degree of divergence, though this is notessential to: the invention.

The engine I33 is illustratively, though. not necessarily, of -a two-cycle. type, and each of cylinders, I34 and I35 is.- accordingly provided. with an. appropriate fuel-air intake pipe I46, air being understood to be drawn in through the flared scoop-end MI thereof, and a; fuel mixture being formed by carburetor I42. Each of,- cylinders. I34 and. I35 is: provided; with an. exhaust. pipe I44 connected in the manner conventional in twocycle engines. These exhaust pipes I41 may discharge to atmosphere preferably in the same direction as the discharge from conduits I30 and i3I (see dotted line indication), but as here shown they are connected to the convergent end portions of the conduits I30 and I3I. In this connection, for a reason which will appear presently, the exhaust from cylinder I33 is introduced to conduit I 3| and the exhaust from cylinder I35 is introduced to conduit I3I Working within cylinders I34 and I35 is a unitary free piston structure I50 consisting of a piston I5I working within cylinder [3d, a piston I 52 working within cylinder I35, and an enlarged acoustic piston I 53 working within enlarged chamber !32, the piston I53 having angular sides I54 of the same angle as the angular end walls I 3 1 of chamber I 32, so that clearance space be tween the acoustic piston I53 and the ends of the chamber I32 may be reduced substantially to zero. The heads of the two cylinders are provided with spark plugs I69, and these are energized under the control of the reciprocation of the free piston. As one illustrative expedient, the piston member I53 may be provided with a cam rod IfiI projecting oppositely there-from and outwardly through suitable close-fitting passages in the endwalls I31 of chamber I 32. Opposite ends of this cam rod are formed with cam surfaces I62 engageable with breaker arms I63. Each of spark plugs I60 is connected .to the high voltage terminal of a conventional induction coil I655, the low voltage circuit of which includes a battery [35 and a make-and-break switch I 66 controlled by breaker arm I63. Thus, at the end of each stroke of the free-piston structure; cam rod I6I operates a breaker arm I63 to open the switch at I66 and break the low voltage circuit, thus causing a spark to occur at plug IG O in the conventional manner.

Upon the occurrence of an explosion, say in cylinder I33, the free-piston is driven downwardly, and the acoustic piston head I53 creates a positive pressure pulse which is introduced into horn I3I and traverses the latter to its open end. The explosion frequency of the engine is easily adjusted to the fundamental resonant frequency of the horns I30 and I3I, which behave substantially as quarter wave cavities, with high impedance pressure anti-node regions P at their ends coupled to the free-piston, and with low impedance velocity anti-node regions V at their open ends. Accordingly, the positive pressure pulse launched, for example, down the horn I3I is. reflected from the open end therof' as. a negative pressure pulse, which arrives with peak negative pressure at the beginning. or smaller end of the horn and at the space in. cylinder I 32 between the horn and. piston portion I53 as the latter. is mid-way on its upward. return stroke. A reflection. of this negative pulse occurs, and a negative pulse travels down the horn, to berefiected from the open end as a positive pulse whichv will pass. through the small end of the horn and arrive at piston portion. I53 withpeak pressure at the mid-point of the downv stroke. Both. sides of. the acoustic piston are thus used for wave generation, the lower cooperating with lower horn I3I, and the upper with upper horn I3I). A polyphase effect is thereby achieved. at the discharge ends of the two horns,, with resulting reduction. of objectionable noise.

Reference isv here made to my continuation-inpart application entitled Acoustic J et Enginewith Centrifugal Fluid Pumping Characteristics, filed 15 April 24, '1950, Serial No. 157,740, in which the subject matter of Figure 2 of the present application is disclosed and claimed.

The broad invention has now been disclosed by way of a specific description of several illustrative embodiments thereof. It is to be understood of course that these are for illustrative purposes only, and that various changes in design, structure and arrangement may be made without departing from the spirit and scope of the invention as claimed.

I claim:

1. A multiple-circuit quarter-wave pulse jet engine comprising a, plurality of substantially quarter-wave fluid filled sonic pipes each substantially closed at a forward end thereof to form a sonic wave reflector, and open at its rearward end for wave expansion and fluid jet discharge, said pipes being grouped and disposed for jet discharge in the same general direction, a pressure pulse means for each of the pipes for producing intermittent positive pressure pulses within the fluid in the closed end portion of the pipe at a frequency to resonate the pipe and establish in the fluid column therein a standing wave having a pressure anti-node at the closed end of the pipe and a velocity anti-node at the open end thereof, all in such manner as to produce fluid velocity oscillations at the open end of each pipe in combination with intermittent jetting of fluid therefrom under control of the corresponding standing wave, and a coupling between said pressure pulse means for the pipes adapted to produce a phase difference between the standing waves in the pipes whereby the velocity oscillations at the open ends of the pipes are out of phase with one another and the jet discharges from the plurality of pipes will occur in succession.

2. An engine as defined in claim 1, wherein the rearward ends of the pipes are disposed in close proximity to one another, so as to provide acoustic intercoupling of the standing waves in the pipes as a result of interaction of fluid velocityoscillations in the region surrounding said velocity anti-nodes.

3. An engine as defined in claim 1, including also means for synchronizing the pressure pulse means to produce standing waves in the sonic pipes having uniform phase difierence.

4. An engine as defined in claim 1, in which the sonic pipes are positioned substantially parallel to one another and side side.

5. An engine as defined in claim 1, in which the sonic pipes are positioned in a longitudinal row, and including means for synchronizing the standing waves in the sonic pipes to operate with uniform phase difference.

' '6. A multiple circuit quarter wave pulse jet engine comprising a plurality of substantially quarter-wave fluid filled sonic pipes each substantially closed at a forward end thereof to form a sonic wave reflector and open at the rearward end thereof for wave expansion and fluid jet discharge, said pipes being grouped and disposed in the same general direction, means for introducing fuel and air to the closed end portion of each of said sonic pipes and for exploding same at a frequency to resonate said pipes and establish in the fluid column therein standing waves having pressure anti-nodes at the closed ends of the pipes and velocity anti-nodes at the open ends thereof, all in such manner as to produce fluid velocity oscillations at the open end of each pipe in combination with intermittent jetting of fluid 16 therefrom under control of the corresponding standing wave, and a coupling acting-to maintain the standing waves in the pipes with a phase difference between them.

'1. An engine as defined in claim 6, wherein-the coupling comprehends an interaction of oscillating fluids surrounding the velocity anti-node regions of the pipes.

8. An engine as defined in claim 6, including also fuel feeding means for the pipes operable and synchronized to feed fuel charges to the sonic pipes at equal time intervals in predetermined succession.

9. An engine asdefined in claim 6, including also a fuel distributor pump adapted to feed fuel charges to the sonic pipes at equal time intervals in predetermined succession.

10. An engine as defined in claim 6, including fuel feeding means for the pipes, and air feeding means operable and synchronized to feed air charges to the sonic pipes at equal time intervals in predetermined succession.

11. A multiple-circuit quarter-wave pulse jet engine comprising a plurality of substantially quarter-wave fluid filled sonic pipes each substantially closed at a forward end thereof to form a sonic wave reflector, and open at its rearward end for wave expansion and fluid jet discharge, said pipes being grouped and disposed for jet discharge in the same general direction, a pressure pulse means for each of the pipes for producing intermittent positive pressure pulses Within the fluid in the closed end portion of the pipe at a frequency to resonate the pipe and establish in the fluid column therein a standing wave having a pressure anti-node at the closed end of the pipe and a velocity anti-node at the open end thereof, all in such manner as to produce fluid velocity oscillations at the open end'of each pipe in combination with intermittent jetting of fluid therefrom under control of the corresponding standing wave, the rearward ends of the pipes being disposed in close proximity to one another, so as to provide acoustic intercoupling of the standing waves in the pipes as a result of interaction of fluid velocity oscillations in the region surrounding said velocity antinodes.

12. A multiple circuit quarter wave pulse jet engine comprising a plurality of substantially quarter-wave fluid filled sonic pipes each substantially closed at a forward end thereof to form a sonic wave reflector and open at the rearward end thereof for wave expansion and fluid jet discharge, said pipes being grouped and disposed in the same general direction, a common pipe surrounding and extending rearwardly from said plurality of pipes, forming a common conduit for receiving the jet discharge from all of said pipes and having a common discharge opening to atmosphere at its rearward end, and means for introducing fuel and air to the closed end portion of each of said sonic pipes and for exploding same at a frequency to resonate said pipes and establish in the fluid column therein standing Waves having pressure anti-nodes at the closed ends of the pipes and velocity anti-nodes at the open ends thereof, all in such manner as to produce fluid velocity oscillations at the open end of each pipe in combination with intermittent jetting of fluid therefrom into said common surrounding pipe under control of the corresponding standing wave.

13. An engine as defined in claim 12, including 17 18 means causing the standing Waves in the sonic REFERENCES CITED pipes to operate with a phase difference.

14 An engine as defined in claim 12 including The following references are of record in the fuel feeding means for the sonic pipes timed to file Of this paifinti establish the standing waves in the pipes with 5 UNITED STATES PATENTS substantially equal phase differences between Number Name Date them.

15. An engine as defined in claim 12, wherein Forsyth Sept 1947 the discharge ends of the sonic pipes are grouped FOREIGN PATENTS in close proximity to one another to cause an in- 0 Number Country Date teraction of oscillating fluids surrounding the 186,749 Great Britain Oct 12 1922 velocity anti-node regions of the sonic pipes and thereby establish a. tendency for acoustic selfcoupling with uniform phase relations between the standing waves in the several pipes. 15

ALBERT G. BODINE, JR. 

